Power has been restored to 12,000 Orion customers in southwest Christchurch.
The outage happened about 7.15pm on Wednesday after a protection system cable failed, lines company Orion says.
Customers in Spreydon, Summerfield, Cashmere, Beckenam and St Martins were affected.
A spokesperson for the company, Rob Jamieson, says workers had to disconnect the cable in order to fix the problem.
Electricity was restored just after 9pm.
Police say there were no problems caused by the power cut.